Gaseous refractory-element molecules in IRC10216

The list of detected refractory-element (RE) species in IRC10216 is now large enough to try to assess their chemistry, and the fraction of each that escapes in gas phase to the ISM. The former may tell us how grains are formed, the latter whether mass-loss from evolved stars is important in determining interstellar elemental depletions as distinct from accretion processes in the ISM. We expect that much of the Si chemistry is now understood and about 25% of Si escapes as a gas. Other REs are less well understood but most should be more volatile than Si. For many of the REs, O-rich CSEs should behave similarly to C-rich ones.Operated by Associated Universities, Inc., under cooperative agreement with the National Science Foundation